JP2002365164A - Optical parameter management method of elliptic polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of managing an optical parameter of an elliptic polarizing plate including a linear polarizing plate and a torsion phase difference film by a simple measuring method. SOLUTION: In this management method of the optical parameter of the elliptic polarizing plate including the linear polarizing plate and the torsion phase difference film, a light source, the elliptic polarizing plate arranged so that the linear polarizing plate side faces to the light source side, a (2n+1)/4 wave plate, and an analyzer are arranged in this order, and light emitted from the light source is allowed to enter the elliptic polarizing plate, the (2n+1)/4 wave plate, and the analyzer in this order, and the optical parameter of the elliptic polarizing plate is managed by the minimum transmissivity wavelength acquired by measuring a transmission spectrum of transmitted light through the analyzer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a simple optical parameter management method for an elliptically polarizing plate.

[0002]

2. Description of the Related Art In recent years, a stretched film manufactured from a polymer film such as polycarbonate, and a liquid crystal film manufactured from a liquid crystal material such as a nematic liquid crystal and a discotic liquid crystal have been used to prevent coloration of a liquid crystal display element, improve contrast, and improve viewing angle. Widely used as a compensator for improvement. Also, with the active development of thin and lightweight reflective or transflective liquid crystal display devices, there is a demand for compensators for liquid crystal display devices with excellent optical characteristics used for these liquid crystal display devices. Is increasing more and more. Particularly, in a reflective or transflective liquid crystal display device using an STN (Super Twisted Nematic) cell, a twisted retardation film is widely used because of its excellent compensation effect as a compensating plate for a liquid crystal display device.

[0003] A twisted phase difference film is a TN cell or S
It is a film having a twist orientation in the film thickness direction like the TN cell. Here, there are retardation and twist angle as important optical parameters of the twist retardation film.
Here, the retardation is represented by the product (△ nd) of the birefringence (△ n) and the film thickness (d). The retardation and the twist angle greatly affect the display quality of the liquid crystal display device. For example, variations from the set values of the retardation and / or the twist angle of the twisted retardation film are found in industrialized products, and when the variation is out of an allowable range, a liquid crystal display device using the film is used. In this case, not only can display quality not be uniformed, but also display quality may be significantly reduced. For this reason, the optical parameters of the twist retardation film must be strictly controlled.

There are several methods for measuring the optical parameters of the twisted retardation film alone. For example, the optical parameters can be measured by the following method. As an optical measurement system, a light source such as a halogen lamp, a polarizer, a twisted phase difference film alone, an analyzer, and a spectrometer are arranged in this order, and the orientation axis on the incident side of the twisted phase difference film and the transmission axis of the polarizer are 0 in the horizontal direction. It is arranged so as to be 45 degrees counterclockwise from this axis. Next, the transmission axis of the analyzer is rotated to detect the transmission axis angle at which the transmittance becomes the minimum, and the wavelength at which the transmittance becomes the minimum, that is, the minimum transmittance wavelength (λmi)
n; unit nm). At this time, the torsion angle can be obtained from the angle of the polarizer and the angle of the transmission axis of the analyzer. Also, using the minimum transmittance wavelength (λmin),
The retardation at the minimum transmittance wavelength (λmin) is obtained from the following equation (1), and the wavelength dispersion characteristic of birefringence is taken into consideration using the following equation (2) called Cauchy's equation. The retardation △ nd (550 nm) can be determined.

Δnd (λmin) = λmin × (I ² − (θ / π) ² ) ^1/2 (1) λmin: minimum transmittance wavelength θ: twist angle of molecules in the liquid crystal layer of the retardation film (unit: degree) ) I: order (0.5, 1, 1.5, 2, 2.5, 3,...) Δnd (λmin) / Δnd (550 nm) = A + B / λ ² + C / λ ⁴ (2) A, B, C: constant

The constants (A, B, C) in the above equation (2)
Depends on the film material of the twisted retardation film, using a sample with no twist of nematic orientation,
40 sample retardation by Senarmont method
It is measured every 10 nm in a wavelength range from 0 nm to 800 nm, and this measured value is determined by fitting with Cauchy's formula.

However, when the product is actually shipped as a product, it usually takes the form of an elliptically polarizing plate in which a linear polarizing plate and a twisted retardation film are integrated. There is a problem that it is difficult to measure and manage the optical parameters of the retardation film. Further, from the viewpoint of product quality control, it is required that optical parameters can be measured as simply as possible, and a technique that can be managed by a commercially available spectrophotometer or the like is desired.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and provides a method for managing the optical parameters of an elliptically polarizing plate including a twisted retardation film and a linear polarizing plate using a simple measuring method. To provide.

[0009]

That is, the first aspect of the present invention is as follows.
Is a method for managing optical parameters of an elliptically polarizing plate including a linearly polarizing plate and a twisted retardation film, and includes a light source, an elliptically polarizing plate in which the light source side is the linearly polarizing plate side, (2n
+1) / 4 wavelength plate (n represents an integer of 0 or more) and an analyzer, and the light emitted from the light source enters the elliptically polarizing plate, the (2n + 1) / 4 wavelength plate, and the analyzer in this order. The present invention also relates to a method for managing optical parameters of an elliptically polarizing plate, wherein the optical parameters of the elliptically polarizing plate are managed by a minimum transmittance wavelength obtained by measuring a transmission spectrum of the transmitted light of the analyzer. Further, the second aspect of the present invention is as follows.
The (2n + 1) / 4 wavelength plate is a 1/4 or 3/4 wavelength plate, and relates to the optical parameter management method for an elliptically polarizing plate described above.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The method for managing the optical parameters of an elliptically polarizing plate of the present invention includes: an elliptically polarizing plate including a twisted retardation film and a linearly polarizing plate, a light source, an elliptically polarizing plate in which the light source side is the linearly polarizing plate side, A four-wavelength plate (n represents an integer of 0 or more) and an analyzer are arranged in this order, and the light emitted from the light source is incident on the elliptically polarizing plate, a (2n + 1) / 4-wavelength plate, and the analyzer in this order. This method uses an optical system to manage optical parameters based on the spectrum of light emitted from the analyzer, that is, the minimum transmittance wavelength of the transmission spectrum.

The linear polarizing plate used in the present invention is not particularly limited, and a polarizing plate usually used for a liquid crystal display device can be appropriately used. Specifically, iodine and / or a dichroic dye is adsorbed and stretched on a hydrophilic polymer film made of polyvinyl alcohol (PVA), partially acetalized PVA, partially saponified ethylene-vinyl acetate copolymer, or the like. A polarizing film made of a polarized film, a polyene oriented film such as a dehydrated product of PVA or a dehydrochlorinated product of polyvinyl chloride, or the like can be used.

The above-mentioned linear polarizing plate may be used alone or as a polarizing film provided with a transparent protective layer or the like on one or both sides of the polarizing film for the purpose of improving strength, moisture resistance, heat resistance and the like. It may be. As a transparent protective layer,
Examples thereof include a transparent plastic film such as polyester or triacetyl cellulose laminated directly or via an adhesive layer, a resin coating layer, and a light and / or thermosetting resin layer such as an acrylic or epoxy resin. When these transparent protective layers are coated on both sides of the polarizing film, the same protective layer may be provided on both sides, or different protective layers may be provided.

The angle formed between the transmission axis of the linear polarizing plate and the slow axis of the surface adjacent to the linear polarizing plate of the twisted retardation film described later is not particularly limited, and the elliptically polarizing plate may have any angle. However, in the present invention, optical parameters can be managed.

The twisted retardation film constituting the elliptically polarizing plate has an optically anisotropic axis and a structure in which the slow axis is twisted from one surface to the other surface.
Therefore, the twisted retardation film referred to here has the same characteristics as those obtained by laminating a plurality of optically anisotropic layers such that their slow axes are continuously twisted in multiple layers. It has a corner.

As the twisted retardation film, a liquid crystal film or a laminate of an optical film such as a stretched film can be used. The liquid crystal film means a film having a structure in which a slow axis is continuously twisted in one film. This liquid crystal film is generally
It can be obtained by forming a liquid crystal material having a twist alignment characteristic into a film. Such a liquid crystal film,
A composition in which a compound having a chiral property is blended with a liquid crystal material having a nematic liquid crystal property, or a liquid crystal material having an optical activity in which a chiral group is introduced is twisted nematically aligned, and then the alignment structure is changed to, for example, photocrosslinking or heat. It can be obtained by a method such as immobilization by cross-linking or a method of fixing in a glass state by cooling.

The liquid crystal material is not particularly limited as long as it has a nematic liquid crystal property, and various low-molecular liquid crystal substances, high-molecular liquid crystal substances, or a mixture thereof can be used as the material. The molecular shape of the liquid crystal material is
Regardless of whether it is rod-shaped or disk-shaped, for example, discotic liquid crystals exhibiting discotic nematic liquid crystal properties can also be used. Further, when these mixtures are used as a liquid crystal material, if the material can finally form a desired twisted structure, and if the alignment structure can be fixed, the composition of the material or There is no limitation on the composition ratio or the like. For example, a mixture of a single or a plurality of low-molecular and / or high-molecular liquid crystal substances, a single or a plurality of low-molecular and / or high-molecular non-liquid crystal substances, and various additives is used as the liquid crystal material. You can also.

Low-molecular liquid crystal substances include Schiff base, biphenyl, terphenyl, ester, thioester, stilbene, tolan, azoxy, azo, phenylcyclohexane, pyrimidine, and cyclohexylcyclohexane. And low molecular liquid crystal compounds having a trimesic acid-based, triphenylene-based, torquecene-based, phthalocyanine-based, and porphyrin-based molecular skeleton, or a mixture of these compounds.

As the polymer liquid crystal material, various kinds of main chain type liquid crystal material, side chain type polymer liquid crystal material, or a mixture thereof can be used. As the main chain type polymer liquid crystal material, polyester, polyamide, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenthiazole, polyazomethine, polyesteramide, polyester carbonate And a liquid crystal material such as a polyesterimide-based polymer, or a mixture thereof. Among these, a semi-aromatic polyester polymer liquid crystal in which bent chains such as a mesogen group and a methylene group or a siloxane group that give liquid crystal properties are alternately bonded, or a wholly aromatic polyester polymer liquid crystal having no bent chain are used. It is desirable in the present invention.

Examples of the side chain type polymer liquid crystal substance include polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, polymalonate and polyester skeleton chains having a linear or cyclic structure. Or a mixture thereof, in which a mesogen group is bonded as a side chain to a substance having the following formula: Among these, a side chain type polymer liquid crystal material in which a mesogen group that provides liquid crystallinity is bonded to a skeleton chain via a spacer consisting of a bent chain, or the polymer having a molecular structure having a mesogen in both the main chain and the side chain. Liquid crystal materials are desirable in the present invention.

It is particularly desirable that the liquid crystal material contains a chiral agent or various liquid crystal materials or non-liquid crystal materials having at least one kind of chiral structural unit in order to induce twisted nematic alignment. . Examples of the chiral structural unit include optically active 2-methyl-1,4-butanediol, 2,4-pentanediol, 1,2-propanediol, and 2-chloro-1,4.
-Butanediol, 2-fluoro-1,4-butanediol, 2-bromo-1,4-butanediol, 2-ethyl-1,4-butanediol, 2-propyl-1,4-
Butanediol, 3-methylhexanediol, 3-methyladipic acid, naproxen derivative, camphoric acid,
Units derived from binaphthol, menthol, or a cholesteryl group-containing structural unit or a derivative thereof (for example, a derivative such as a diacetoxy compound) can be used.

The above-mentioned chiral structural unit may be either an R-form or an S-form, or may be a mixture of the R-form and the S-form. . Note that these structural units are merely examples, and the present invention is not limited thereto.

When the alignment structure formed in the liquid crystal state is fixed by thermal crosslinking or photocrosslinking when preparing a liquid crystal film, a functional group or site capable of reacting by heat or photocrosslinking reaction or the like is added to the liquid crystal material. It is desirable to mix various liquid crystal substances having the same. Examples of the functional group capable of performing a cross-linking reaction include an acryl group, a methacryl group, a vinyl group, a vinyloxy group, an allyl group, an allyloxy group, an epoxy group, an isocyanate group, an isothiocyanate group, an azo group, a diazo group, an azoxy group, and an azide group. , Hydroxyl group, carboxyl group, lower ester group and the like,
Particularly, an acryl group and a methacryl group are desirable. Examples of the site capable of undergoing a cross-linking reaction include sites having a molecular structure such as maleimide, maleic anhydride, cinnamic acid and cinnamate, alkene, diene, arene, alkyne, disulfide, and polysulfide. These cross-linking groups and cross-linking reaction sites may be contained in the various liquid crystal substances constituting the liquid crystal material itself, but a non-liquid crystal substance having a cross-linking group or cross-linking reaction sites may be separately added to the liquid crystal material.

Another example that can be used as a twisted retardation film is an optical film such as a stretched film having a pseudo twisted structure in which the optically anisotropic axis is twisted continuously like the liquid crystal film. A laminate can be given. The film is generally formed of a uniaxial transparent plastic film represented by a polycarbonate-based, cellulose-based, polyarylate-based, polysulfone-based, polyacryl-based, polyethersulfone-based, polynorbornene-based, cyclic olefin-based resin, or the like. Stretching or
It can be formed by biaxial stretching. By laminating a plurality of these films with their respective slow axes shifted little by little, a twisted retardation film can be produced.

The optical parameters of the twisted retardation film used in the present invention are not particularly limited, but the wavelength is 550 nm.
Is particularly effective when the product Δnd of the birefringence Δn and the thickness d (nm) of the twisted retardation film with respect to the above light is 270 nm or less. For this reason, when Δnd is larger than 270 nm, the minimum transmittance of the transmission spectrum can be obtained without disposing a (2n + 1) / 4 wavelength plate.
However, when Δnd is 270 nm or less, (2n + 1) /
If the four-wavelength plate is not used, the minimum value does not appear in the transmission spectrum of the elliptically polarizing plate including the four-wavelength plate, or even if the minimum value appears, the shape of the transmission spectrum becomes very broad and the minimum value is obtained with high accuracy. The transmittance wavelength may not be obtained in some cases. In the present invention,
The slow axis of the (2n + 1) / 4 wavelength plate is arranged at an arbitrary angle in a plane perpendicular to the optical path in the optical path.

Here, the (2n + 1) / 4 wavelength plate is not particularly limited, and may be, for example, polycarbonate, cellulose, polyarylate, polysulfone, polyacryl, polyethersulfone, polynorbornene. , A retardation plate formed by stretching a transparent plastic film represented by a cyclic olefin plastic or the like, a nematic liquid crystal or a smectic liquid crystal,
Examples include a retardation plate formed by orienting a liquid crystal material such as discotic liquid crystal, and a retardation plate formed of birefringent crystal such as calcite or quartz.

The (2n + 1) / 4 wavelength plate is not particularly limited, but when n = 0 or 1, that is, a 1/4 wavelength plate or a 3/4 wavelength plate is particularly desirable in the present invention. When n = 2 or more, that is, when a wavelength plate larger than the ５ wavelength plate is used, the minimum transmittance wavelength of the transmission spectrum of the elliptically polarizing plate can be obtained, but the minimum transmittance wavelength can be obtained even when the parameter is shifted. It does not fluctuate much, and in terms of parameter management, a quarter wave plate or 3 /
Most preferably, a four-wave plate is used.

In the analyzer used in the present invention, the transmission axis of the analyzer is arranged at an arbitrary angle in a plane perpendicular to the optical path in the optical path. The analyzer may be either a rotary type or a fixed type. As the analyzer of the present invention, the same analyzer as the linear polarizing plate can be used. Another example is an analyzer constituted by a polarizing prism or the like made of a birefringent crystal.
The spectrum of the light transmitted through the analyzer is measured by a spectrometer or a spectrometer. Alternatively, a spectrum is measured by inserting a combination of the elliptically polarizing plate, the (2n + 1) / 4 wavelength plate, and the analyzer into a measurement optical path of a commercially available spectrophotometer. The minimum transmittance wavelength (λmin) may be obtained from the obtained spectrum.

[0028]

According to the method for managing optical parameters of an elliptically polarizing plate of the present invention, the optical parameters of an elliptically polarizing plate including an industrially mass-produced twisted retardation film and the optical parameters of a single twisted retardation film can be obtained. The measurement can be easily performed by measuring the minimum transmittance wavelength of the elliptically polarizing plate as a product without measuring the wavelength.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
In addition, the retardation (Δnd) in the present embodiment.
Is a value at a wavelength of 550 nm unless otherwise specified.

Reference Example 50 mmol of terephthalic acid, 50 mmol of 2,6-naphthalenedicarboxylic acid, 40 mmol of methylhydroquinone diacetate, 60 mmol of catechol diacetate,
Using 60 mg of N-methylimidazole and a nitrogen atmosphere, polymerization was carried out at 270 ° C. for 12 hours. Next, the obtained reaction product was dissolved in tetrachloroethane, and then purified by reprecipitation with methanol to obtain 14.7 g of a liquid crystalline polyester. The logarithmic viscosity of this liquid crystalline polyester (Polymer 1) is 0.17 dL / g (0.5 g / dL;
A phenol / tetrachloroethane (6/4 weight ratio) mixed solvent, 30 ° C.), a nematic phase as a liquid crystal phase, an isotropic phase-liquid crystal phase transition temperature of 250 ° C. or higher, and a glass transition point of 115 ° C.

Biphenyl dicarbonyl chloride 90 mm
ol, 10 mmol of terephthaloyl chloride, and S
-2-methyl-1,4-butanediol 105 mmol
Was reacted in dichloromethane at room temperature for 20 hours, and the reaction solution was poured into methanol for reprecipitation to obtain 12.0 g of a liquid crystalline polyester. The logarithmic viscosity of this liquid crystalline polyester (polymer 2) is 0.12 dL / g.
(0.5 g / dL; phenol / tetrachloroethane (6/4 weight ratio) mixed solvent, 30 ° C.).

A solution was prepared by dissolving 19.82 g of the polymer 1 and 0.18 g of the polymer 2 in 80 g of a phenol / tetrachloroethane mixed solvent (6/4 weight ratio).
This solution was applied on a rubbed polyimide film (manufactured by DuPont, trade name: Kapton), and after the solvent was removed by drying, the mixture was heat-treated at 230 ° C. for 5 minutes to form a twisted orientation structure. And then cooled to room temperature to fix the torsional alignment structure in a glassy state to obtain a liquid crystal film uniformly aligned on a polyimide film (liquid crystal film 1).

An 80 μm triacetyl cellulose film (Fuji Photo Co., Ltd.) was placed on the air interface side of the obtained liquid crystal film 1 through an approximately 5 μm thick UV-curable adhesive (UV-3400, manufactured by Toagosei Co., Ltd.). A film (trade name: FUJITAC T80SZ) was bonded. Next, after UV irradiation, the polyimide film was peeled and removed, and furthermore, UV light was applied to one surface of the liquid crystal film from which the polyimide film had been removed.
A curable adhesive (UV-3400, Toagosei Co., Ltd.) layer was formed and cured to obtain a twisted retardation film 1.

Similarly, by changing the mixing ratio of polymer 1 and polymer 2, twisted retardation films 2 to 5 having the same structure as twisted retardation film 1 were obtained. The retardation and twist angle of the twisted retardation film obtained alone were determined by the following methods.

As a light source, a halogen lamp (PHL-100 manufactured by Medilo Precision Co., Ltd.), a polarizer (Sigma MINI-60), a twisted phase difference film alone, an analyzer (Sigma MINI-60), a spectrophotometer (Photonic multi-channel analyzer PMA-11 manufactured by Hamamatsu Photonics Co., Ltd.) in order. The orientation axis on the incident light side of the twisted phase difference film and the transmission axis of the polarizer are 0 in the horizontal direction.
It is arranged so as to be 45 degrees counterclockwise from this axis. Next, the transmission axis of the polarizer is rotated to detect the transmission axis angle at which the transmittance becomes minimum, and obtain the wavelength at which the transmittance becomes minimum, that is, the minimum transmittance wavelength (λmin). The torsion angle (θt) can be obtained from the angle of the polarizer and the angle of the transmission axis of the analyzer at this time. Table 1 shows the results.

[0036]

[Table 1]

Further, each of the minimum transmittance wavelengths (λm
in) and their minimum transmittance wavelengths correspond to I = 0.5 order, and using these values, the retardation at the minimum transmittance wavelength (λmin) is obtained from equation (1). Further, the retardation at a wavelength of 550 nm was determined. Table 2 shows the results. The constants (A, B, C) in the equation (2) are obtained by measuring the retardation of a twist-free nematic alignment film separately prepared only with the polymer 1 by the Senarmont method in a wavelength range of 400 to 800 nm at intervals of 10 nm. The value was determined while applying the value to equation (2).

Δnd (λmin) = λmin × (I ² − (θ / π) ² ) ^1/2 (1) λmin: minimum transmittance wavelength (unit: nm) θ: molecules in the liquid crystal layer of the retardation film Torsion angle (unit: degree) I: order (0.5, 1, 1.5, 2, 2.5, 3,...) Δnd (λmin) / Δnd (550 nm) = A + B / λ ² + C / λ ⁴ (2) A: 0.8666 B: 2.53 × 10 ⁻¹⁴ C: 4.56 × 10 ⁻²⁷

[0039]

[Table 2]

Examples Twisted retardation films 1 to 5 obtained in Reference Examples 1 to 5
A polarizing plate (manufactured by Sumitomo Chemical Co., Ltd., SR1862AP) was bonded via a μm pressure-sensitive adhesive layer to obtain elliptically polarizing plates 1 to 5. The arrangement of the polarizing plate and the twisted phase film at this time is as shown in FIG. The minimum transmittance wavelength of the obtained elliptically polarizing plates 1 to 5 was measured by the following method. First, the elliptically polarizing plate 1 is perpendicular to the optical path and the side of the linear polarizing plate is a halogen lamp light source (PHL-10 manufactured by Medilo Precision Co., Ltd.).
The light is emitted from a light source to the elliptically polarizing plate 1 to extract elliptically polarized light. This elliptically polarized light is made of polycarbonate 1/4 which is installed so that the slow axis is at 90 degrees in the XY plane perpendicular to the optical path.
An analyzer (Sigma optical instrument MI) that is incident on a wave plate (△ nd = 137 nm) and is further set so that the transmission axis is at 50 degrees.
NI-60). The transmission spectrum of the light transmitted through this analyzer is measured by a spectrophotometer (Hamamatsu Photonics Co., Ltd.
Photonic multi-channel analyzer PMA-1
Minimum transmittance wavelength λm at which the transmittance is minimized, detected in 1)
The measured in was 538 nm. The axis arrangement of the elliptically polarizing plate, quarter-wave plate and analyzer at this time is as shown in FIG. Λ of elliptically polarizing plates 2 to 5 measured in the same manner
Table 3 shows min. When the same measurement was performed using an analyzer with an ultraviolet / visible / near infrared spectrophotometer V-570 manufactured by JASCO Corporation, a value similar to the value shown in Table 3 was obtained.

[0041]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a layout view of a transmission axis of a linear polarizer and a molecular orientation axis in a twisted phase liquid crystal layer viewed from a light source side (right side: not shown).

FIG. 2 is an axial arrangement diagram of an elliptical polarizing plate, a quarter-wave plate, and an analyzer viewed from a light source side (right side: not shown) for implementing a parameter management method of the elliptical polarizing plate of the present invention.

[Explanation of symbols]

 Reference Signs List 1 retardation film 2 twist angle of molecules in liquid crystal layer 3 orientation axis on linear polarizing plate side 4 linear polarizing plate 5 transmission axis 6 1/4 wavelength plate 7 1/4 wavelength plate orientation axis (90 degrees) 8 analyzer 9 Analyzer transmission axis (50 degrees)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsuya Uesaka 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Prefecture Nishiishi Mitsui Co., Ltd. Central Research Laboratory F-term (reference) 2G086 EE10 2H049 BA02 BA04 BA06 BA26 BA27 BA42 BB03 BB42 BB43 BC01 BC04 BC22 2H091 FA08X FA08Z FB02 FC07 KA10 LA12

Claims (2)

[Claims] 1. A method for managing optical parameters of an elliptically polarizing plate including a linearly polarizing plate and a twisted retardation film, comprising: a light source, an elliptically polarizing plate in which the light source side is the linearly polarizing plate side, (2n + 1) / A four-wavelength plate (n represents an integer of 0 or more) and an analyzer are arranged in this order, and the light emitted from the light source is incident on the elliptically polarizing plate, a (2n + 1) / 4-wavelength plate, and the analyzer in this order. An optical parameter management method for an elliptically polarizing plate, wherein an optical parameter of the elliptically polarizing plate is managed by a minimum transmittance wavelength obtained by measuring a transmission spectrum of light transmitted by an analyzer. 2. The method according to claim 1, wherein the (2n + 1) / 4 wavelength plate is a 1/4
2. The method according to claim 1, wherein the optical parameter is a ／ wavelength plate.